The unambiguous detection and characterization of special nuclear materials (SNM), particularly shielded highly enriched uranium at standoff distances and weapons grade plutonium, is a challenging problem. Recently, that problem has become even more acute due to the worldwide shortage of 3He—the neutron converter isotope for the leading SNM neutron detectors.
3He used in industry is manufactured as a product of tritium decay. Tritium can be produced through neutron bombardment of deuterium, lithium, boron, or nitrogen targets. Production of tritium in significant quantities requires the high neutron flux of a nuclear reactor. Current supplies of 3He come, in part, from the dismantling of nuclear weapons. Because the need for warhead disassembly is diminishing, tritium is now in short supply. Because current production method for 3He employs conversion of tritium, tritium needs to be produced at the same rate as 3He, and tritium must generated continually because tritium decays with a half life of about 12.32 years. Because there is not enough facility to generate tritium, the current shortage of 3He is expected to continue into the future, and is likely to be exacerbated.